Whilst I personally consider 24/192 overkill for a variety of reasons, the statement above is typically born of complete & utter ignorance, cloth ears or lousy monitoring. The difference between 16/44.1 and 24/96 is almost night & day to me.

night and day might be stretching it!!! Definitely a difference but only if you're in an environment capable of resolving those differences. Reminds me of the vinyl debate - most cheap turntables and rooms they're installed in render the lovely shortcomings yet pleasing euphoria surrounding records largely left to the imagination!

Which has absolutely nothing to do with the subject.
This process, according to what I read, only talks about "capturing Bias for archive" and says nothing about this being necessary in the digital domain.

Not to mention the obvious problem - different machines have different biasing frequencies & I have been supplied - by major labels - with 24/192 transfers clearly showing several biasing spikes.

Which has absolutely nothing to do with the subject.
This process, according to what I read, only talks about "capturing Bias for archive" and says nothing about this being necessary in the digital domain.

Not to mention the obvious problem - different machines have different biasing frequencies & I have been supplied - by major labels - with 24/192 transfers clearly showing several biasing spikes.

The bias was never meant to be used as time-code. I suspect that even top-grade tape recorders use low precision signal generators, probably with substantial drift and noise (at least, that's what I would expect). However, the idea to use this information to improve wow and flutter is very interesting indeed.

The bias in itself is a hack to make magnetic tape work "sufficiently OK" for audio tasks. It is by no means related to musical information. Technically it can be seen as a distortion of the original information. The simplified model basically describes a linear process (a simple mix) that can be easily filtered away. However, magnetic tape is inherently non-linear and will create non-harmonic IMD products, which somehow corrupt the idea. I wonder how strong these effects really are in reality...

In short, I suspect that designers of magnetic tape recording equipment would certainly get rid of bias altogether if they could control the magnetic hysteresis problem by different means.

This discussion of capturing the latent Bias signal from the tape refers to the technology developed by Jamie Howarth of Plangent Processes which, in oversimplified terms, uses the bias recovered from the tape as a reference to time-correct the audio, reducing or eliminating wow, flutter, speed drift, and most importantly, IM distortion caused by the deficiencies of the tape transport. Plangent is effective on even the best-sounding masters, and has been used on reissues by the Grateful Dead, Bruce Springsteen, Queen, Doc Watson, Pete Seeger, and many others, including feature films. It requires a specialized wide-bandwidth replay head and electronics, plus analysis gear for the capture. There are several facilities, including Airshow, that are equipped for this. The processing itself is done at Plangent in Massachusetts. Contact Plangent for more info, or send me a message. This technology is the only new thing in our industry that has really excited me in the past decade.

It would appear to be basically an extension to the technology they developed for Melodyne DNA, with an extra level of analysis where pitch variations due to wow and flutter are distinguished from desired variations such as vibrato.

There is also Cedar's Respeed for their Cambridge system. Both Respeed and Celemony's Capstan are a completely different approach to Plangent and the other systems and with extremely mixed results.

As always it comes down to time, budget, and intent. Often there is no time, no budget or you do not have access to the original physical source and so the software is a very workable solution in those situations. But, with both time and budget, the hardware systems always win the day and often the dedicated systems are much closer to satisfying and exceeding the intent of the client.

Situation A is the most common but would prefer to always be in Situation B.

You mean you're not excited about all the analog modeled plug-ins, DIY multi-band solutions, Har-Bal, and LANDR?

Wow!

};~)>

Best, JT

that's what i was thinking! Even things I don't like or use personally are still incredible. Melodyne DNA (okay - it aint a band-aid but its still pretty tech!), visual based noise processing using 20 years of graphic knowledge to remove sonic artefacts, acoustics developments and solutions (seriously - remember how big our studio rooms had to be 20 years ago?) .... the list goes on!

This debate may finally have been put to rest. Here's an abstract from a paper about to be presented at AES in October. Key quote:

Two main conclusions are offered: first, there exist audible signals that cannot be encoded transparently by a standard CD; and second, an audio chain used for such experiments must be capable of high-fidelity reproduction.

This paper describes listening tests investigating the audibility of various filters applied in high-resolution wideband digital playback systems. Discrimination between filtered and unfiltered signals was compared directly in the same subjects using a double-blind psychophysical test. Filter responses tested were representative of anti-alias filters used in A/D (analog-to-digital) converters or mastering processes. Further tests probed the audibility of 16-bit quantization with or without a rectangular dither. Results suggest that listeners are sensitive to the small signal alterations introduced by these filters and quantization. Two main conclusions are offered: first, there exist audible signals that cannot be encoded transparently by a standard CD; and second, an audio chain used for such experiments must be capable of high-fidelity reproduction.
Convention Paper 9174

I was at this paper. As far as the “outcome” it’s just as the precis states: There are musical signals that cannot be recorded with 100% transparency in 44/16. Nothing earth-shattering. The study was interesting in the way the blind testing was done (not A/B/X, only “same” or “different”) and the results, while statistically significant, where by no means dramatic.

I can't remember where the test was/who conducted it but it was done with an old version of Pyramix's sample rate converter. Even then, there were better SRCs out there.

If you go on the SRC Comparisons site you'll see how bad Pyramix is. The passband in the old version was not flat at all and those tiny ripples are definitely audible. From that "scientific test" it was concluded that high sample rates are better.

You just don't know who to trust these days. So my suggestion? Take some high resolution recordings. Convert them with a decent sample rate converter and do a null test. Coming to my own conclusions, PONO is a way for Neil Young to make more money. He squandered his chance to talk to the media during his various high profile interviews about the loudness wars ruining music.

But then, that would have brought into question the usefulness of PONO/high res audio for consumer playback and Mr. Young wouldn't want any more scrutiny, would he?

I was at this paper. As far as the “outcome” it’s just as the precis states: There are musical signals that cannot be recorded with 100% transparency in 44/16. Nothing earth-shattering. The study was interesting in the way the blind testing was done (not A/B/X, only “same” or “different”) and the results, while statistically significant, where by no means dramatic.

I urge anyone interested in this stuff to get the AES paper.

DC

It doesn't seem to me that the results of this paper can confidently support the conclusion that there are some signals which cannot be encoded with 100% transparency in a 44.1 kHz and 16 bit system (or as they say, in a standard CD).

Why? -- they tested no truncation, truncation and RPDF + truncation. The rationale for RPDF vs TPDF given in section 2.3 is this:

Quote:

We chose to use undithered quantization as a probe and — although we would normally recommend TPDF dither for best practice — we considered rectangular dither to be more representative of the non-ideal dither or error-feedback processing found in some commercial A/D and D/A filters.

(this is a bit of a red flag TBH, because with CD playback, the truncation, with or without appropriate dither, has already taken place before writing the signal to CD, so trying to be representative of processing that occurs later on, in the playback chain, rather than of the CD itself seems to me like an oversight. It also seems to assume that the DAC is 16 bit, which is not common anymore.)

From section 2.1:

Quote:

This level was chosen for comfort, and because it was high enough for details to be audible but also low enough that 16bit RPDF dither would be inaudible at the listening position [30].

From the discussion in section 4.1:

Quote:

Every condition where 16-bit quantization was applied gave performance that was significantly better than chance. Performance was significantly worse for 16-bit quantization plus RDPF dither than for no quantisation or 16-bit quantization alone. This suggests that the effect of adding the RPDF dither on top of the 16-bit quantization and FIR filtering was to make it more difficult to identify that processing had been applied to the signal, which is perhaps counterintuitive.

(It is not that counterintuitive if one understands what dither does and how.)

They go on to speculate why this might be the case, citing feedback from subjects such as "some said that they found it easier to discriminate the signals when the passage in the trial contained echoes" (this is the kind of feedback one expects when listening to signals that have been bit depth reduced without appropriate dither). But, they do not discuss the possibility that TPDF or some form of noise shaped dither, used instead of RPDF, may have resulted in even worse discrimination than the RPDF processing did.

So, there was a decision made to attempt to configure the processing-under-test such that it represented real-world CD playback with some (not all!) commercial CD players. The presented conclusions in section 5 quite rightly do not explicitly include the result that there exist audible signals that cannot be encoded transparently by a standard CD, because that conclusion is not well supported by the design and results of the test!

But unfortunately, that is the summarised conclusion which made it into the abstract, so is the one the vast majority of people are going to read and remember, despite it being inaccurate.

Too nitpicky? It might be, but we don't know because their test design was not thorough enough to know how much the choice of RPDF vs TPDF or various noise shaped dithers affected the results. Just goes to show, always read more than the abstract.

edit -- were there any questions about this, and/or extrapolation from the authors at the paper session?

Of course there's things that can't be accurately recreated at 16/44 - the room, the air, the center, and the timbre of instruments and voices. All the things that make the primary signal sound better.

Some of us hear it clear as day, others choose to believe scientists over musicians and mathematicians over their own ears. It's sad to me that even on GS people act like this is settled science.

Your science knows next to nothing about how the human auditory system uses spatial data, timing cues, and amazingly flexible focus (like mixed resolutions and location tracking, but liquid based) to do it's magic.

No robot can hear like a human. If they had half the understanding of the math behind music their would be robots amongst us, singing, talking, preforming hit songs, etc..

Some of us hear it clear as day, others choose to believe scientists over musicians and mathematicians over their own ears.

Bob is right. Just because you hear something doesn't mean your experiment is not totally flawed. The modern distrust of science in favour of feelings and/or faith is becoming the world's undoing. How do you think we have reached the current level of civilisation?

Your science knows next to nothing about how the human auditory system uses spatial data, timing cues, and amazingly flexible focus (like mixed resolutions and location tracking, but liquid based) to do it's magic.

Acoustics, human hearing, audio and science are inseparable. When something is called magic it is usually related to illusion, bias, or lack of knowledge of proved science. The former two are intended and unintended phenomenons respectively, the latter one- is just negligence.
The good news is that understanding of all the matters can be easily gained today with just a little will. The bad news is that only few do it, others choose to hone beliefs.

Your science knows next to nothing about how the human auditory system uses spatial data, timing cues, and amazingly flexible focus (like mixed resolutions and location tracking, but liquid based) to do it's magic.

I highly recommend you to become member of the AES and browse through their library for a while. Or as a start, read Helmholtz's classic "The sensation of tone" from 1836 (!). You'll wonder how much is known about music perception. Understand this book and you'll maybe have an idea what happened during these 180 years since then.

IMO, you are radically underestimating the state of science in 2015. MP3 alone wouldn't be possible without solid knowledge about auditory perception.

Actually I understand a lot of the very best information wound up in IEEE papers and unfortunately not AES. The first thing my college music psychology teacher did in 1966 was introduce us to research from Bell Labs that conflicted with a lot of Helmholtz's ideas. I only wish I remembered the details better.